The fopen family of functions in C is
normally used for reading configuration files, since fgets is an easy
way to parse files on a line-by-line basis. The INKfopen family of functions aims at solving
the same problem of buffered IO and line at a time IO in a platform-independent manner. The
fopen family of C library functions can only open a
file if a file descriptor less than 256 is available. Since Traffic Server
often has more than 2000 file descriptors open at once, however, the
likelihood of an available file descriptor less than 256 very small. To solve this problem, the
INKfopen family can open files with descriptors
greater than 256.
The INKfopen family of routines is not
intended for high speed IO or flexibility - they are blocking APIs (not asynchronous). For performance reasons, you should not
directly use these APIs on a Traffic Server thread (when being called back on an
HTTP hook); it is better to use a separate thread for doing the blocking
IO. The INKfopen family is intended for reading and
writing configuration information when corresponding usage of the fopen family of functions is inappropriate due to file descriptor and
portability limitations. The INKfopen family of
functions consists of the following: